get_maintainer: fix usage comment

With the `s' it just won't work.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/get_maintainer.pl

@@ -5,8 +5,8 @@
 # Print selected MAINTAINERS information for
 # the files modified in a patch or for a file
 #
-# usage: perl scripts/get_maintainers.pl [OPTIONS] <patch>
-#        perl scripts/get_maintainers.pl [OPTIONS] -f <file>
+# usage: perl scripts/get_maintainer.pl [OPTIONS] <patch>
+#        perl scripts/get_maintainer.pl [OPTIONS] -f <file>
 #
 # Licensed under the terms of the GNU GPL License version 2